The present invention relates to conveyors and automatic warehousing systems, and in particular to apparatus for the storage and retrieval of objects in warehouses. Specifically, the invention relates to apparatus for the storage and retrieval of relatively thin trays or sheets having cylindrical nuclear materials resting thereon.
A typical warehouse includes numerous storage bins or locations in which objects are stored until needed. Each storage bin has a specific address, that is a set of coordinates by which it can be identified and distinguished from other storage locations. In most instances rows of racks are positioned on either side of an aisle. The racks include a plurality of storage locations identified by their vertical height and horizontal position along the aisle.
In an automated warehouse system, a truck or cart having an object handler mounted thereon moves up and down the aisle, selectively retrieving an object from one of the storage locations, or selectively storing an object therein.
In a typical warehouse, the object to be stored is a large package or the like. Often, in such systems, the package is stored upon pallet-like extensions in the storage bin. The package may then be readily accessed from underneath and lifted from the pallets and removed from the storage bin. Object engagement mechanisms which accomplish this are generally fork or tongue extensions which extend from the cart to a position underneath the package, and which are then lifted to engage the package, in a manner somewhat analogous to a fork lift lifting an object from the surface of a pallet. With such devices, the package is held upon the object engagement mechanism solely by gravity. Extension or retraction of the tongue moves the package into or out of the storage bin. When the package is supported outwardly of the storage bin, motion of the truck or cart moves the package about the warehouse.
A major problem with such conventional systems is that the object to be stored is not positively engaged by the object handler mounted on the cart. Rather, the package is merely held on the object handler by means of gravity and friction. Thus, it can be relatively easily jostled off of the cart during transportation.
In some industries, the object to be stored or transported is a relatively shallow tray or a thin sheet of material. In some instances, it may be desired to simply store the tray or sheet itself; in others, small objects may rest inside the tray or on top of the sheet and it is the small objects themselves which are of concern. Conventional warehousing systems have not been completely successful in handling the storage of such items.
In particular, in the nuclear industry, relatively small elongate cylinders of nuclear material are often handled and stored. It may be important to maintain the cylinders at a selected distance separated from one another, even when more than one cylinder rests on a single thin tray or sheet. The cylinders may be relatively securely supported by a corrugated tray, with the cylinders resting in depressions caused by the corrugations. In this manner, they will not roll about the tray and come into contact with one another. However, automatic warehousing systems having object handlers specifically developed for secure handling of such corrugated trays have heretofore not been available.
In industries such as the nuclear industry it is generally important that the thin tray or sheet be securely held by the object handler, so that risk of accident is somewhat minimized. Previous types of object handlers have not been completely successful in obtaining this result.
In some industries it may be important that the object handler be capable of accessing the thin sheet from either end. For example, the thin tray may be removed from the right side of an aisle, transported by the cart, and stored on the left side of the aisle. This generally requires that the object handler be capable of positively engaging the thin sheet on either of its ends.
A possible advantage to the storing of small objects on relatively shallow trays or thin sheets is that they may be stored with the sheets in relatively close vertical proximity to one another. That is, the vertical distance between each tray can be relatively small. However, conventional object handlers in warehousing systems have generally required substantial vertical space for their operation, making it more difficult to fully realize the space conserving advantage to the utilization of shallow trays or thin sheets for the storage of objects.
In a large warehouse having numerous storage bins, a great many trays or sheets might be necessary for efficient operation. It would be preferable that the sheets not have special attachments or extensions thereon, so that they may be relatively inexpensively made. Further, such special attachments or extensions might become caught on the rack, or portions of the handler, increasing the possibility of accidents. Conventional methods of handling trays generally require extensions on the trays which are engaged by a portion of the handler. It is readily seen that the avoidance of such special attachments or extensions is preferred.
The problems outlined above, and various other problems discussed below, were not satisfactorily resolved until the emergence of the instant invention.